An antimicrobial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. A variety of chemical compounds, natural or synthetic, have been used as antimicrobials. Antimicrobial drugs either kill microbes (microbicidal) or prevent the growth of microbes (microbistatic). For example, disinfectants are antimicrobial substances used on non-living objects. Antimicrobial agents have also been used to control the growth of microorganisms in a variety of industrial processes. Hospital disinfectants, medical device materials may include antimicrobials to prevent infection of patients. Antimicrobials are found in commercial settings, particularly to disinfect contaminated surfaces, as well as in a variety of industrial or household products such as foods, cosmetics, furniture, paints, paper, oil, textile and wood products.
Mixtures of antimicrobial agents have been used for certain applications. For example, a combination of agents may provide antimicrobial effects against a broader spectrum of microbes than a single agent can. A broad spectrum coverage is especially useful in applications where multiple and diverse microorganisms are often encountered. Also, a combination of antimicrobials can make the agents more effective when the antimicrobial composition is to be used for an extended course of treatment. The targeted microbes will have more difficulties to adapt to multiple active ingredients. Moreover, complexes of agents have also been attempted, which have different, yet complementary, physiochemical properties (e.g., U.S. Pat. Nos. 5,629,263 and 3,639,632), although only cationic antimicrobials are generally used together (e.g., U.S. Pat. No. 5,891,921). The anionic, cationic and non-ionic antimicrobial agents are rarely used together due to the potential antagonistic effects.
Despite many antimicrobials are commercially available, problems with effectiveness, sustainability, bioavailability, safety, environmental acceptability, and/or cost remain. Antimicrobials that are ideal for particular applications continue to be sought after. Microorganisms are becoming resistant to current antimicrobial agents. For example, bacteria found in hospital settings are becoming especially drug resistant. There are significant unmet needs for new and improved antimicrobial compounds, compositions, and methods of using the same, particularly compounds that are antiseptic, antifungal, bacteriocidal, bacteriostatic and algae-proofing.